Method and apparatus for measuring permeability



Sept. 7,- 1948. w.-A. BRUCE. l 2,448,955

ETHOD AND APPARATUS FOR HEASURING PQERIEABILITY Filed June 1, 1945 V ATTORNEY.

Patented Sept. 7, 1948 i N2,448,955 'A 2.448.955 Mn'rnon AND APrAnA'rUs ron MEASUR- .PlmMnAnm'rr ING William A. Bruce, Tulsa, Okla., assigner to Standard Oil Development Company, a corporation of Delaware l Application June l. 1945, Serial No. 597.016

z claim. lol. 'lssal` 'Ihe present invention is directed to a method and apparatus for the determination of the permeability of rock cores and other consolidated Porous bodies. y The principal object of the present invention is the provision of a method and lapparatus by use of which the permeability of a core obtained during the drilling of a well. or in any other manner. may vbe approximated rapidly anden the spot.

In essence, the method of the present invention consists in amxing to the core in any suitable manner a suction device, building up a vacuum on the surface of the core and then observing over a predetermined period the decrease of the vacuum.

`The nature of the present invention may -be more clearly understood from the following de- .tailed description of the accompanying drawing;

which is a vertical section of one type of appara- Y, tus suitable for the practice of the present inven` Referring to the drawing in detail i designates a container in which is deposited ya bed 2 of loose une sand. or other highly permeable material. Extending through Ithe core I of the container is a pump '4 which is simply a cylinder provided with Ia piston I fand a stem l having a handle 1. Ailixed to the 'cylinder at a point below the uppermost point of travel of the piston is a pressure gauge i. The lower part of the cylinder is nrovided with a plug 'l of soft rubber having a central passageil. Y

In the use of this apparatus a core fragment Il having a substantially fiat surface is selected.

'Ille plug I is pressed against the fiat surface and a layer of rubber cement l'! is applied to the flat surface in such a way to seal the lower end of the cylinder tothe iiat surface. It may be mentioned here that the core fragment is preliminarily treated to remove most of any liquid which it may have contained. 'I'his may be done conve'niently by placing the core fragment in a sui able centrifuge for the removal of liquid.

In the actual field practice of this method i-t is not necessary to use the container I. It ig sufilclent to substitute for the rubber cement a soft rubber disc which can be pressed against the core sample by the operator handling the sample in one hand and the pump in the other hand. Where possible. it is more convenient to use the assembly Ihm ln the drawing.

' When the core sample is -properly afilxed to the pump as shown -in the drawing, the piston is pulled upwardly to a point above the pressure gauge to apply` suction to the core. The reading in the pressure gauge at the end of the stroke is observed. It is again read at five second intervals, until the pressure returns .to atmospheric. or to any predetermined value below atmospheric. This increase in pressure after the vertical stroke will i be due to the passage of air inte the core from the exterior. The rate at which the pressure builds up will be a direct function of the permeability of the core sample. This reading can be taken as an approximation of the permeability lli of the material of which the core is constituted.

The natureand objects of the present invention having been thus described and illustrated. what is claimed as new and useful and is desired to be secured by Letters Patent is:

so `1. A method for determining the permeability of a rock core from a fragment thereof which n comprises selecting a fragment of said core of irregular configuration having at least one substantially fiat face, arranging said fragment in a lbed of loose particles with said substantially flat face exposed. building up a vacuum on said substantially flat face and observing the rate at which said vacuum is dissipated. l

l2. A device for determining the permeability 80 of a consolidated porous body comprising a tubu- -lar pump having a reciprocating plunger, a layer of soft. conformable, impervious material attached to the suction end of 'said pump and arranged around the intake thereof in such a manner that said layer can be pressed against said porous body 40 WILLIAM A. BRUCE.

REFERENCES CITED The following references are of record-in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 1,887,132 Harpst Apr. 13. 1920 o 1,421,903 Buben July 4, 1922 2.345.985 Lewis Nay 18, 1944 2,355,858 Hahn et al Aug. 15, 1944 

